P1573: VARIATION IN USE OF IMMUNOGLOBULIN AND IMPACT ON SURVIVAL IN MULTIPLE MYELOMA: A REPORT FROM THE AUSTRALIA/NEW ZEALAND (ANZ) AND ASIA-PACIFIC (APAC) MYELOMA AND RELATED DISEASES REGISTRIES (MRDR)
Authors: K. L. Chai, C. Wellard, N. Aoki, E. M. Moore, B. Augustson, A. Bapat, H. A. Blacklock, W. J. Chng, R. Cooke, C. Forsyth, N. Hamad, S. J. Harrison, P. J. Ho, J. Hocking, I. H. Kerridge, J. S. Kim, K. Kim, T. King, G. J. McCaughan, P. Mollee, C. O. Morrissey, N. Murphy, H. Quach, X. N. Tan, A. Tso, K. Wong, A. Spencer, E. M. Wood, Z. K. McQuilten
Journal: HemaSphere (2022)

Background: Serious infection is common in patients with multiple myeloma (MM), and associated with major morbidity and mortality. Immunoglobulin (Ig) replacement is frequently used to reduce infections, but this is based on small trials conducted >20 years ago. Guidelines for Ig use in MM patients vary between countries. Use of Ig and associated costs are increasing worldwide. Aims: This study aims to outline Ig use in the “real-world MM” setting, identify variation in practice and predictors of use, and describe association with survival outcomes. Methods: Retrospective review of patients registered on the ANZ and APAC MRDR with a diagnosis of MM or plasma cell leukaemia from sites with verifiable data regarding Ig. Survival and cause of death data (COD) was augmented via linkage with national death registries for ANZ patients. Patient/disease characteristics, therapy and survival were compared between patients who received Ig by 24 months of diagnosis and patients who did not, using chi-square tests for categorical variables and rank sum tests for continuous variables. Variation in Ig use across sites was compared. Kaplan-Meier survival analysis was used to estimate duration of Ig use. Time-dependent Cox analysis was used to compare survival for patients whilst on and off Ig therapy. All statistical analysis was completed on STATAv16.1. Results: 2445 patients with a median follow-up time of 30 months were included in this analysis - 1744 from Australia (12 sites), 313 Korea (3 sites), 281 New Zealand (1 site) and 107 Singapore (3 sites). Of patients reaching 12-month follow-up post MM-diagnosis, 6.4% received Ig and of patients reaching 24-month follow-up, 7.0% received Ig. 69% of these Ig-users were estimated to receive over 24 months duration of Ig. Administration varied by country – between 0 to 17% of patients by country who reached 24 months follow-up received Ig. Patients who received Ig by 24 months of MM-diagnosis were younger, had lower baseline IgG and Ig levels, more likely to have abnormal FISH, receive first-line IMiDs, anti-CD38 therapy and ASCT (Table 1). Ig use was not associated with overall survival benefit (HR=0.72, 0.46-1.14, p=0.16). Baseline Ig levels were also not found to be associated with overall survival. At time of last follow-up, there were 623 deaths (25.4%). Available data on COD was available for 175 deaths in ANZ patients. Of these, 65 deaths (37.1%) had infection listed as primary/secondary COD. 64 of these 65 infection-related deaths occurred in patients who did not receive Ig. In patients who received Ig (at any time), 12.5% had infection as primary/secondary COD, compared to 38.5% in non-recipients (p=0.14). Image:Summary/Conclusion: In this real-world cohort, use of Ig varied between countries and was associated with lower baseline IgG, abnormal FISH, and first-line therapy with IMiD, anti-CD38 and ASCT. Ig use was not associated with overall survival, highlighting the need for contemporary studies to inform patient selection, especially with rising use of Ig and targeted anti-myeloma therapies, and a high burden of infection-related mortality.